Overview
Sickle cell disease is a lifelong condition. It represents a group of hemoglobin-related disorders that are inherited from parents to their offspring. Sickle cell are abnormally-shaped red cells, as they appear like crescent moon or sickles, in stead of the normal round disc shapes.
It should be noted that an individual can have sickle cell trait in their genes, but they do not manifest sickle cell disease.
How It Occurs
Genetics of sickle cell disease.
Hb A, codes for normal beta chain of hemoglobin
Hb S, codes for abnormal hemoglobin beta chain of hemoglobin
Sickle cell anemia is an autosomal recessive disorder, therefore an individual must inherit two copies of the mutated hemoglobin gene, one from each parent, in order to develop the condition.
For sickle cell anaemia, mutation occurs in the Hb gene( at the beta globin sub-unit of the Hb molecule).
This mutation An adenine for thymine (A for T) substitution in the sixth codon replaces glutamic acid with valine in the 6th position of the beta globin chain. Hb S, the mutated fprm of Hb, forms long, insoluble and rigid fibrils in low oxygen tension or when deoxygenated. This leads to the characteristic sickle cell of red blood cells.
Epidemiology
Globally, more than 20,000,000 people are affected.
SCD is a rare condition in the USA.
It affects only around 70,000 to 100,000 persons.
In terms of ethnicity/ race, it mostly affects African Americans. Of all African -Americans, approximately 8% are affected.
It is more prominent in areas that are mostly affected with malaria. This comes with an advantage, in that it offers partial protection against malaria.
According to statistics;
- About 1 in every 13 African-American babies are born having sickle cell trait.
- About 1 in every 365 African-American babies are born with SCD.
Causes
SCD is a genetic condition. This means that it is passed down in families through their genes.
In this condition, red cells are shaped like sickles or crescent moons, which are irregular shapes.
The normal regular shape for red cells is round round discs.
The normal cells are flexible while the sickle cells are stiff and sticky.
Risk Factors
- Genetics. Being born to parents who both have sickle cell genes.
- Race. It is more common is specific racial communities, such as individual of African descent, hispanics and Asians.
Signs & Symptoms
In young babies, sickle cell anemia can lack symptoms for up to several months after birth. Symptoms can begin showing 4 months after birth.
When symptoms surface, these may be;
- Fatigue
- Selling in the hands and feet
- Jaundice
- Damaged spleen
- Anaemia. Sickle red blood cells have an ultra-short lifespan of 10-20 days whereas normal RBCs live for 120 days. This extremely short lifespan leads to decreased numbers of red cells and hemoglobin. This causes anaemia.
- Painful and vaso-occlusive crises.
- Frequent infections. Bacterial infections as a result of damaged spleen. When the spleen is damaged, immune system is affected and chances for bacterial infections occurring increase.
- Dark urine.
- Stunted/ retarded growth.
Diagnostic Tests
Diagnosis involves obtaining a properly-detailed patient history, and other diagnostic techniques such as lab tests.
Prenatal diagnosis;
A test on the amniotic fluid
Post-natal diagnosis;
Blood tests are conducted as part of newborn screening tests.
Hemoglobin tests, a second blood tests, confirms the diagnosis.
Treatment & Management
Currently, methods used to treat the condition are;
- Allogenic stem cell transplantation
- Bone marrow transplant
Transplantation is recommended by clinicians for individuals with severe complications such as stroke.
Treatment of sickle cell anaemia involves;
- Series of blood transfusions
- Antibiotics to combat bacterial infections
- Medications that reduce symptoms that are caused by complications.
Such medications include;
- Hydroxyurea
- L-glutamine therapy
Also, administer folic acid supplements. Folic acid is a haematinic; it will aid in erythropoiesis(red blood cell formation)
Complications
- Stroke. Stroke can occur due to blockage of vessels in the brain
- Acute chest syndrome. It occurs as a result of inflammation and infections.
- Organ damage
- Avascular necrosis
- Frequent infections. Bacterial infections as a result of damaged spleen. When the spleen is damaged, immune system is affected and chances for bacterial infections occuring increase.
- Deep vein thrombosis(DVT).
- Sickle cell sequestration in the spleen. This happens when irregular red cells are rapped in the spleen and it becomes very large.
- Pulmonary hypertension
- Leg ulcers
- Priapism. This refers to painful, long-lasting erections among males with the condition.
- Increased risk of miscarriage, premature birth and giving birth to babies with low weights
- Blindness
Ways of Prevention
- Since this is an inherited condition, early screening for sickle cell trait is recommended.
- Individuals should get tested to check if they have the trait, which can be passed down to their offsprings.
- If present, genetic counselling of couples is advised, especially before marriage or pregnancy.